Check if a user can send message in a mentioned channel discord.js

I have a command which allows users to make the bot to say a message, but I would like it to be able to check whether the user is able to send messages in that channel before it sends it. Currently, I just have it locked to the MANAGE_MESSAGES permission.

Here is the code:

if (message.member.hasPermission("MANAGE_MESSAGES")) {
    let msg;
    let textChannel = message.mentions.channels.first();

    message.delete();

    if (textChannel) {
        msg = args.slice(1).join(" ");
        if (msg === "") {
            message.channel.send("Please input a valid sentence/word.")
        } else {
            textChannel.send(`**Message from ${message.author.tag}:** ${msg}`)
        }
    } else {
        msg = args.join(" ");
        if (msg === "") {
            message.channel.send("Please input a valid sentence/word.")
        } else {
            message.channel.send(`**Message from ${message.author.tag}:** ${msg}`)
        }
    }
} else {
    message.reply('You lack the required permissions to do that. (Required Permissions: ``MANAGE_MESSAGES``)')
}

I have searched and couldn’t find much on this, any help is appreciated

Answer

I’m not sure if I understand your question correctly. You can check if the member has permission in a certain channel using channel.permissionFor(member).has('PERMISSION_NAME'). I’m not sure if you really wanted the user to have MANAGE_MESSAGES permission, I think SEND_MESSAGES should be enough, so I used that in my code below. I also made it a bit cleaner and added some comments:

const mentionedChannel = message.mentions.channels.first();
// if there is no mentioned channel, channel will be the current one
const channel = mentionedChannel || message.channel;

message.delete();

// returns true if the message author has SEND_MESSAGES permission
// in the channel (the mentioned channel if they mentioned one)
const hasPermissionInChannel = channel
  .permissionsFor(message.member)
  .has('SEND_MESSAGES', false);

// if the user has no permission, just send an error message and return
// so the rest of the code is ignored
if (!hasPermissionInChannel) {
  return message.reply(
    `You can't send messages in ${mentionedChannel}. You don't have the required permission: `SEND_MESSAGES``,
  );
}

const msg = mentionedChannel ? args.slice(1).join(' ') : args.join(' ');

if (!msg) {
  // send an error message in the same channel the command was coming
  // from and return
  return message.reply('Please input a valid sentence/word.');
}

// if the user has permission and has a message to post send it to the
// mentioned or current channel
channel.send(`**Message from ${message.author.tag}:** ${msg}`);